IS NOT NULL is replaced by '>= -1E38' in alternates giving by SQL Optimizer. What does that d (4241867)

When running a statement through SQL Optimizer that contains 'IS NOT NULL', some of the alternates that SQL Optimizers gives me in its results has '>= -1E38' instead of 'IS NOT NULL'. What is '>= -1E38' and what does it do?

Example...

Original SQL:
select * from Table1
where col1 IS NOT NULL;

Alt SQL:
select * from Table1
where col1 >= -1E38;

When your SQL retrieves data using the condition "col1 is not null", Oracle would not be able to use the index on the "col1" column to retrieve data for you. The transformation that changes the condition to "col1 >= -1E38" is mainly trying to make it possible for Oracle to consider using the index on the "col1" column. The value "-1E38" is the smallest number that you can store in the "col1" column, so searching all data >= -1E38 means searching any non-null values.